اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدMY Serpentis: a high-mass triple system in the Ser OB2 association
102
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We present spectroscopic observations of the massive multiple system HD,167971, located in the open cluster NGC,6604. The brighter component of the triple system is the overcontact eclipsing binary MY,Ser with an orbital period of 3.32,days. The radial velocities and the previously published UBV data obtained by citet{may10} and the UBVRI light curves by citet{dav88} are analysed for the physical properties of the components. We determine the following absolute parameters: for the primary star M$_p$=32.23$pm$0.54 M$_{odot}$, R$_p$=14.23$pm$0.75 R$_{odot}$; and for the secondary star M$_s$=30.59$pm$0.53 M$_{odot}$, R$_s$=13.89$pm$0.75 R$_{odot}$. Photoelectric times of minimum light are analyzed under the consideration of the light-time orbit. The center-of-mass of the eclipsing binary is orbiting around the common center-of-gravity of the triple system with a period of 21.2$pm$0.7,yr and with a projected semi-major axis of 5.5$pm$0.7,AU. The mass function for the third star was calculated as 0.370$pm$0.036 M$_{odot}$. The light contributions of the third star to the triple system in the UBV pass-bands were derived and the intrinsic magnitudes and colors were calculated individually for the three stars. The components of the eclipsing pair were classified as O7.5 {sc iii} and O9.5 {sc iii}. The intrinsic color indices for the third star yield a spectral type of (O9.5-B0) {sc iii-i}. {bf This classification leads to constrain the inclination of the third-body orbit, which should be about 30$^{o}$, and therefore its mass should be about 29 M$_{odot}$. MY,Ser is one of the rare massive O-type triple system at a distance of 1.65$pm$0.13,kpc, the same as for the NGC,6604 embedded in the Ser,OB2 association.}
قيم البحث
اقرأ أيضاً
Aiming to explore weak spectral features of stellar and interstellar origin we used the NES echelle spectrograph of the 6-m telescope to obtain high-resolution spectra for 13 hot O3 - B4 stars in the Cyg OB2 association, including a high luminous sta
r No. 12. Velocity fields in the atmospheres and interstellar medium, characteristics of optical spectra and line profiles are investigated. The cascade star formation scheme for the association is confirmed. Evidence is presented suggesting that the hypergiant Cyg OB2 No.12 is an LBV object and that its anomalous reddening has a circumstellar nature.
Massive binary stars may constitute a substantial fraction of progenitors to supernovae and gamma-ray bursts, and the distribution of their orbital characteristics holds clues to the formation process of massive stars. As a contribution to securing s
tatistics on OB-type binaries, we report the discovery and orbital parameters for five new systems as part of the Cygnus OB2 Radial Velocity Survey. Four of the new systems (MT070, MT174, MT267, and MT734 (a.k.a. VI Cygni #11) are single-lined spectroscopic binaries while one (MT103) is a double-lined system (B1V+B2V). MT070 is noteworthy as the longest period system yet measured in Cyg OB2, with P=6.2 yr. The other four systems have periods ranging between 4 and 73 days. MT174 is noteworthy for having a probable mass ratio q<0.1, making it a candidate progenitor to a low-mass X-ray binary. These measurements bring the total number of massive binaries in Cyg OB2 to 25, the most currently known in any single cluster or association.
Equal-mass stars in young open clusters and loose associations exhibit a wide spread of rotation periods, which likely originates from differences in the initial rotation periods and in the primordial disc lifetimes. We want to explore if the gravita
tional effects by nearby companions may play an additional role in producing the observed rotation period spread. We measure the photometric rotation periods of components of multiple stellar systems and look for correlations of the period differences among the components to their reciprocal distances. In this paper, we analysed the triple system AU Mic + AT Mic A&B in the 25-Myr beta Pictoris Association. We have retrieved from the literature the rotation period of AU Mic (P = 4.85d) and measured from photometric archival data the rotation periods of both components of AT Mic (P = 1.19d and P = 0.78d) for the first time. Moreover, we detected a high rate of flare events from AT Mic. Whereas the distant component AU Mic has evolved rotationally as a single star, the A and B components of AT Mic, separated by about 27 AU, exhibit a rotation rate a factor 5 larger than AU Mic. Moreover, the A and B components, despite have about equal mass, show a significant difference (about 40%) between their rotation periods. A possible explanation is that the gravitational forces between the A and B components of AT Mic (that are a factor about 7.3 x 10^6 more intense than those between AU Mic and AT Mic) have enhanced the dispersal of the AT Mic primordial disc, shortening its lifetime and the disc-locking phase duration, making the component A and B of AT Mic to rotate faster than the more distant AU Mic. We suspect that a different level of magnetic activity between the A and B components of AT Mic may be the additional parameter responsible for the difference between their rotation periods.
We have performed a WISE (Wide-Field Infrared Survey Explorer) based study to identify and characterize young stellar objects (YSOs) in 12x12 degree Perseus OB2 association. Spectral energy distribution (SED) slope in range of 3.4-12 micron and a 5si
gma selection criteria were used to select our initial sample. Further manual inspection reduced our final catalog to 156 known and 119 YSO candidate. The spatial distribution of newly found YSOs all over the field shows an older generation of star formation which most of its massive members have evolved into main sequence stars. In contrast, the majority of younger members lie within the Perseus molecular cloud and currently active star forming clusters such as NGC1333 and IC348. We also identified additional 66 point sources which passed YSO selection criteria but are likely AGB stars. However their spatial distribution suggests that they may contain a fraction of the YSOs. Comparing our results with the commonly used color-color selections, we found that while color selection method fails in picking up bright but evolved weak disks, our SED fitting method can identify such sources, including transitional disks. In addition we have less contamination with background sources such as galaxies, but in a price of loosing fainter (Jmag > 12) YSOs. Finally we employed a Bayesian Monte Carlo SED fitting method to determine the characteristics of each YSO candidate. Distribution of SED slopes and model driven age and mass confirms separated YSO populations with suggested three age groups of younger than 1 Myr old, 1-5 Myr old, and older than 5 Myrs which agrees with the age of Per OB2 association and currently star forming sites within the cloud.
Our goal is to determine the stellar and wind properties of seven O stars in the cluster NGC2244 and three O stars in the OB association MonOB2. These properties give us insight into the mass loss rates of O stars, allow us to check the validity of r
otational mixing in massive stars, and to better understand the effects of the ionizing flux and wind mechanical energy release on the surrounding interstellar medium and its influence on triggered star formation. We collect optical and UV spectra of the target stars which are analyzed by means of atmosphere models computed with the code CMFGEN. The spectra of binary stars are disentangled and the components are studied separately. All stars have an evolutionary age less than 5 million years, with the most massive stars being among the youngest. Nitrogen surface abundances show no clear relation with projected rotational velocities. Binaries and single stars show the same range of enrichment. This is attributed to the youth and/or wide separation of the binary systems in which the components have not (yet) experienced strong interaction. A clear trend of larger enrichment in higher luminosity objects is observed, consistent with what evolutionary models with rotation predict for a population of O stars at a given age. We confirm the weakness of winds in late O dwarfs. In general, mass loss rates derived from UV lines are lower than mass loss rates obtained from Ha. The UV mass loss rates are even lower than the single line driving limit in the latest type dwarfs. These issues are discussed in the context of the structure of massive stars winds. The evolutionary and spectroscopic masses are in agreement above 25 Msun but the uncertainties are large. Below this threshold, the few late-type O stars studied here indicate that the mass discrepancy still seems to hold.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
